Resumo Objetivo Avaliar a introdução de parasitos branquiais de Oreochromis niloticus na bacia do rio Paranapanema, norte do Paraná, sul do Brasil, assim como inventariar suas ocorrências em pisciculturas brasileiras e discutir os riscos de transmissão para a fauna nativa. Métodos As brânquias de 632 espécimes de peixes de quatro estações de piscicultura na bacia do rio Paranapanema foram analisadas. Os parasitos foram coletados, processados e identificados de acordo com procedimento específico. A revisão da literatura foi realizada para compilar registros de ocorrência de espécies parasitas branquiais em outras bacias hidrográficas brasileiras. Resultados Um total de sete (7) espécies de parasitos foi registrado, sendo cinco (5) do gênero Cichlidogyrus, uma (1) de Scutogyrus (Ancyrocephalidae, Monogenoidea) e uma (1) de Lamproglena, Lamproglena monodi (Copepoda, Lernaeidae), todas nativas da África. Algumas dessas espécies foram registradas em pisciculturas localizadas em outras cinco bacias hidrográficas brasileiras. No entanto, neste estudo, um número maior de espécies parasitas africanas foi registrado em pisciculturas no norte do Paraná (sete espécies), na bacia do rio Paranapanema, sendo Cichlidogyrus rognoni relatada apenas para essa bacia. Conclusões Os resultados confirmam a introdução destes parasitos africanos juntamente com o hospedeiro O. niloticus e o estabelecimento dessas espécies em águas brasileiras, uma vez que muitos espécimes pertencentes às espécies aqui identificadas apresentaram atividade reprodutiva por pelo menos um período do ano. Embora apenas L. monodi tenha sido registrada parasitando espécies nativas brasileiras, dados relatados para outros países demonstram o risco iminente de transmissão desses parasitos de O. niloticus para ciclídeos nativos.

Abstract Aim To evaluate the introduction of Oreochromis niloticus gill parasites in the Paranapanema River basin, northern Paraná, southern Brazil, as well as to inventory its occurrences in Brazilian fish farms and discuss the risks of transmission to native fauna. Methods The gills of 632 fish specimens from four fish farms in the Paranapanema Basin were analyzed. The parasites were collected, processed and identified according to specific procedure. Literature review was carried out to compile records of occurrence of gill parasites species in other Brazilian river basins. Results A total of seven (7) species of parasites were recorded, five (5) of the genus Cichlidogyrus, one (1) of Scutogyrus (Ancyrocephalidae, Monogenoidea) and one (1) of Lamproglena, Lamproglena monodi (Copepoda, Lernaeidae). All native from Africa. Some of these species have been reported in fish farms located in five other Brazilian watersheds. However, in this study a greater number of African gill parasite species was recorded in fish farms in northern Paraná (seven species), in the Paranapanema Basin, with Cichlidogyrus rognoni reported only for this basin. Conclusions The results confirm the introduction of these African parasites along with their host, O. niloticus, and the establishment of these species in Brazilian waters, since many specimens belonging to the species identified herein presented breeding activity for at least one period of the year. Although, only L. monodi has been recorded parasitizing Brazilian native species, data reported for other countries demonstrates the imminent risk of transmission of these O. niloticus parasites to native cichlids.

During investigation on the helminth parasites from Brycon hilarii Valenciennes, 1850 (Characiformes, Characidae), from River Juba, Tangará da Serra, state of Mato Grosso, Brazil, several specimens of the nematode Neocucullanus Travassos, Artigas et Pereira, 1928 were detected. A detailed study of this material, including scanning electron microscopy, allowed to identify these nematodes as N. neocucullanus Travassos, Artigas et Pereira, 1928 and to confirm N. multipapillatus Petter, 1989 as a junior synonym of N. neocucullanus.

It is described the histopathology of the infection of Tilapia rendalli (Osteichthyes, Perciformes, Cichlidae) and Hypostomus regani (Osteichthyes, Siluriformes, Loricariidae) by lasidium larvae of Anodontites trapesialis (Mollusca, Bivalvia, Mycetopodidae). The larvae were encysted within the epidermis of the host, being surrounded by a thin hyaline membrane, 3-6 µm thick, of parasite origin. A proliferative host cell reaction did not occur. The histopathology of the infection shows that the lesions induced by the parasites are minimal. However, the numerous small lesions produced by the release of the larvae may provide optimal conditions for the infection by opportunistic pathogens, namely fungus, which may eventually cause the death of the host.

Data obtained between 1990 and 1995 provide, for the first time, ecological information of the parasitic nematode Travassosnema travassosi travassosi Costa, Moreira & Oliveira, 1991 from Acestrorhynchus lacustris (Characiformes: Acestrorhynchidae) collected in the Tibagi River, Sertanópolis, Paraná, Brazil. These nematode occurred with low prevalences (7.7% to 28.6%) and intensities (1 to 3) during almost the whole year. The observation of mature females throughout the year indicate that liberation of larvae can occur during all the year around. This is the first report on the occurrence of T. travassosi travassosi inside the eyes. These nematodes were mostly located in humour of the eyes (87% of cases), being less frequently detected in tissues behind the eyes (13% of cases).

Foi realizado um estudo da comunidade bacteriana de peixes e da água do rio Congonhas, próximo à sua foz no rio Tibagi, município de Sertaneja, Paraná, Brasil. De 44% dos peixes analisados, foram isoladas estirpes de Pseudomonas, Acinetobacter, Aeromonas, Enterobacteriaceae, Micrococcus, Bacillus e Lactobacillus. Destas, a mais abundante foi Aeromonas. Na água do rio Congonhas foram detectados os grupos Pseudomonas, Acinetobacter, Aeromonas, Enterobacteriaceae, Bacillus e Flavobacterium, dos quais os predominantes foram Flavobacterium e Acinetobacter. Os números de unidades formadoras de colônias por mililitro de água variaram entre 3,1x10² e 1,0x10³. Embora não tenha sido detectado um padrão claro nas resistências das diferentes estirpes a nove substâncias antimicrobianas, tais resistências foram observadas em maior número entre as bactérias Gram negativas aeróbias. Foi observada muito freqüentemente uma resistência simultânea à furazolidona, ao ácido oxolínico e à norfloxacina, sobretudo nas bactérias isoladas dos peixes e nas aeróbias isoladas da água. Os antibióticos aos quais foram observadas menos resistências foram a oxitetraciclina, nas bactérias isoladas da água, e o trimetoprim-sulfametoxazol, a oxitetraciclina e o cloranfenicol, nas estirpes isoladas dos peixes.

A bacteriological study was conducted on fish and water from Congonhas River, Sertaneja (22º58’ S; 50º58’ W), Paraná State, Brazil. From 44% of the analysed fish, bacteria belonging to Pseudomonas, Acinetobacter, Aeromonas, Enterobacteriaceae, Micrococcus, Bacillus and Lactobacillus were isolated. The group most frequently isolated from fish was Aeromonas. In the water, the bacterial groups detected were Pseudomonas, Acinetobacter, Aeromonas, Enterobacteriaceae, Bacillus and Flavobacterium, from which Flavobacterium and Acinetobacter were the most abundant. The numbers of Colony Forming Units per millilitre of water varied from 3.1x10² to 1.0 x 10³. Although a clear pattern was not detected in the susceptibilities/resistances of the isolated strains to nine antimicrobial substances, Gram negative aerobic bacteria were more resistant than the other strains. A simultaneous resistance to furazolidone, oxolinic acid and norfloxacin, particularly in the bacteria isolated from fish, as well as in the aerobic strains isolated from water was observed. The antimicrobial substances to which less resistances were found were oxytetracycline in the strains isolated from water, and trimethoprim-sulphamethoxazole, oxytetracycline and chloramphenicol in those isolated from fish.